Implants, such as dental implants, are well known in the art, e.g., U.S. Pat. No. 5,368,483 (Sutter), U.S. Pat. No. 8,029,283 (Schwarz) and US 2010/0068674 (Zucker) incorporated by reference herein.
Dental implants generally comprise an anchoring part, which is designed to be anchored in the jaw bone, and a mounting part, which serves as a base for the direct or indirect attachment of a suprastructure, such as a crown or bridge.
There are one-part dental implant systems, in which the anchoring part and the mounting part are integrally formed of one piece, and two-part dental implant systems, comprising a separate piece, the so-called “abutment”, serving as a mounting part.
An abutment is thus a separate mounting part for a dental implant, intended for connecting the part that is anchored in the bone to the suprastructure.
Dental implants generally consist of a material, which is biocompatible and which additionally has favourable mechanical properties.
With regard to the anchoring part, it is required that the dental implant provides good osteointegration.
The term “osteointegration” designates the direct structural and functional connection between living bone and the surface of the load-bearing implant. A good osteointegration means that the implant, after reaching a primary stability by screwing it into the bone, safely ossifies within a short healing time so that a permanent bond between implant and bone is obtained.
Suitable materials for an implant are in general made of a metal, e.g. titanium, or a ceramic, e.g. a zirconium based ceramic.
In contrast to titanium implants, which are dark and therefore mismatch with the colour of natural teeth, ceramic materials have the advantage that their colour can be closely matched to the colour of natural teeth. Efforts have thus been made to provide dental implants, of which at least the parts that are visible after insertion are made of a ceramic material.
Despite these favourable properties, the use of ceramic materials for dental implants is quite often limited by their fatigue stability, which is generally rather low.
A ceramic material with sufficient mechanical stability is disclosed in U.S. Pat. No. 6,165,925. This material is, however, per se not osteointegrative.
Osteointegration has been turned out to be particularly efficient if mechanical roughening of the implant's surface is combined with subsequent etching of the roughened surface. In this regard, EP-A-1 982 670 discloses a process wherein at least a part of the surface is etched with a solution comprising hydrofluoric acid.
However, a further improvement of the osteointegrative properties of the implant is still the subject of on-going research, since it allows a permanent bond between implant and bone to be established in a relatively fast manner, ultimately allowing a shortening of the healing time after the implantation.